On a known machine of this type, the tool-carrying arms are almost rectilinear and comprise work tools near their outside ends. The work tools generally appear in the form of forks provided with coils to increase their flexibility. The forks are all located on the same side in relation to the longitudinal axes of rotation of their support arms. Consequently, there are considerable imbalances at the level of the support arms when they rotate around their axes during work. These imbalances cause vibrations of the machine and a rapid wear of the bearings guiding the tool-carrying arms and of the mechanisms which control their rotation.